The Gravity Recovery and Climate Experiment (GRACE) has already celebrated its 13th anniversary on 17 March 2015 and the mission operations team is doing its utmost to make the gap to GRACE-FO (Follow-on) as short as possible. The latest RL05 long-term time series of monthly gravity field solutions provided by the GRACE Science Data System shows notable improvements in terms of accuracy, reliability and spatial resolution and offers the opportunity to observe mass transport in the Earth system such as the continental hydrological cycle, surface and deep ocean currents or ice mass loss in Polar Regions.
The Gravity field and steady-state Ocean Circulation Explorer (GOCE) has successfully completed its mission in October 2013. During its final mission phase the satellite flew at an altitude of about 224 km, which represents the lowest height of any research satellite ever been in orbit. Since March 2009 it has delivered a time series of highly accurate gradiometer and satellite-to-satellite tracking data, which formed the basis for GOCE-only and combined static gravity field solutions. The final Rel. 5 GOCE models, incorporating the complete mission data set and exhibiting a significant higher spatial resolution, have been made available to the user community in summer 2014. These models, for the time being, represent the best estimate of the mean geoid one can observe from space and enable various new or improved applications in oceanography, geophysics, geodesy and other Earth sciences.
The great success of GRACE and GOCE, both providing indispensable data for climate research studies, clearly shows that also in the future gravity and its variability has to be monitored from space. Therefore, various initiatives are ongoing to prepare for future gravity mission: Simulation studies have been performed, user and mission requirements have been defined and potential measurement equipments and orbit scenarios have been investigated. Most promising is the US/German GRACE Follow-on (GRACE-FO) mission which is currently in Phase C/D with an anticipated launch date in August 2017.
This session solicits contributions about (1) results from the GRACE and GOCE missions in terms of data analyses and Earth science applications, (2) combination and synergies of GRACE and GOCE targeting on combined gravity field solutions, and (3) status and study results of future gravity field missions.